Revenue - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Monthly resident fees	$ 45.8	$ 45.8	$ 49.7
Revenue recognized		76.2
Additions for allowance for doubtful accounts	4.5	13.4
Deferred Revenue and Credits
Disaggregation of Revenue [Line Items]
Deferred revenue	$ 103.6	$ 103.6	$ 112.4

Contract With Customer, Liability, Deferred Revenue

No definition available.

Name:	bkd_ContractWithCustomerLiabilityDeferredRevenue
Namespace Prefix:	bkd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contract With Customer, Liability, Deferred Revenue, Monthly Resident Fees

+ References

No definition available.

+ Details

Name:	bkd_ContractWithCustomerLiabilityDeferredRevenueMonthlyResidentFees
Namespace Prefix:	bkd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in the allowance for doubtful accounts.

+ References

No definition available.

+ Details

Name:	us-gaap_AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BalanceSheetLocationAxis=bkd_DeferredRevenueAndCreditsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: